添加Sn-5%Zr粉末对激光焊接钢/铝显微组织和性能影响
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摘要
对1.4 mm厚的DP590双相钢和1.2 mm厚的6016铝合金平板试件进行添加Sn-5%Zr(质量分数,下同)粉末的激光搭接焊试验,利用卧式金相显微镜、扫描电镜(SEM)、X射线衍射仪(XRD)、背散射电子衍射技术(EBSD)和微机控制的电子万能试验机等研究了添加Sn-5%Zr粉末对焊缝微观形貌、焊接区域金相组织、断口形貌、主要物相、相的分布及含量、晶粒大小与接头力学性能的影响,采用基于密度泛函理论的第一性原理方法,计算了添加Sn-5%Zr粉末后新形成物相Fe Sn、Fe3Sn和Fe3Al、Fe Al、Fe2Al5等Fe-Al金属间化合物的模量。结果表明,添加Sn-5%Zr粉末钢/铝接头平均剪切强度为37.90 MPa,与未添加粉末相比,剪切强度提高,新形成Zr Al3化合物细化了钢/铝界面Fe-Al金属间化合物的晶粒尺寸,Sn抑制Al向焊缝熔池内扩散,减少Fe-Al金属间化合物层厚度,新形成物相Fe Sn,Fe3Sn具有较好的延性,Sn-5%Zr粉末改变了界面层Fe-Al金属间化合物脆性相与延性相的比例,添加粉末增加焊缝熔宽,提高焊合率,因而添加Sn-5%Zr粉末改善了焊接接头的力学性能。
The laser welding test with Sn-5%Zr(mass fraction) powder addition is carried out on the DP590 dual phase steel with thickness of 1.4 mm and the 6016 aluminum alloy with thickness of 1.2 mm. By using optical microscopy, scanning electron microscopy(SEM), X-ray diffraction(XRD), electron backscatter diffraction(EBCD)and tensile test, the effect of Sn-5%Zr powder addition on the microstructure, fracture morphology, main phase,content and distribution of phase, grain size and mechanical properties of joints are studied. Elastic moduli are calculated by using first-principle method based on density functional theory for Fe Sn, Fe3 Sn, Fe3 Al, Fe Al and Fe2Al5 compounds. The results indicate that the average shear strength of the welding sample with Sn- 5%Zr powder reaches 37.90 MPa. Compared with that without Sn-5%Zr powder addition,the average shear strength of welded joint increases. Because of the formation of Zr Al3 compounds, it promotes the refined grain size of Fe- Al intermetallic compound in aluminum/steel interface, Al spreads to the molten pool is inhibited by Sn, the thickness of Fe-Al intermetallic compound layer is reduced, Fe Sn and Fe3 Sn intermetallic compounds have better ductility,the proportion to brittleness and ductility phases of the interface layer Fe-Al intermetallic compounds are changed,the weld width and bonding rate effectively increased, which can improve the mechanical properties of weld joint with Sn-5%Zr powder addition.
The laser welding test with Sn-5%Zr(mass fraction) powder addition is carried out on the DP590 dual phase steel with thickness of 1.4 mm and the 6016 aluminum alloy with thickness of 1.2 mm. By using optical microscopy, scanning electron microscopy(SEM), X-ray diffraction(XRD), electron backscatter diffraction(EBCD)and tensile test, the effect of Sn-5%Zr powder addition on the microstructure, fracture morphology, main phase,content and distribution of phase, grain size and mechanical properties of joints are studied. Elastic moduli are calculated by using first-principle method based on density functional theory for Fe Sn, Fe3 Sn, Fe3 Al, Fe Al and Fe2Al5 compounds. The results indicate that the average shear strength of the welding sample with Sn- 5%Zr powder reaches 37.90 MPa. Compared with that without Sn-5%Zr powder addition,the average shear strength of welded joint increases. Because of the formation of Zr Al3 compounds, it promotes the refined grain size of Fe- Al intermetallic compound in aluminum/steel interface, Al spreads to the molten pool is inhibited by Sn, the thickness of Fe-Al intermetallic compound layer is reduced, Fe Sn and Fe3 Sn intermetallic compounds have better ductility,the proportion to brittleness and ductility phases of the interface layer Fe-Al intermetallic compounds are changed,the weld width and bonding rate effectively increased, which can improve the mechanical properties of weld joint with Sn-5%Zr powder addition.
引文
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22 Yu W Y,Wang N,Xiao X B,et al..First-principles investigation of the binary AB2 type Laves phase in Mg-Al-Ca alloy:Electronic structure and elastic properties[J].Solid State Sci,2009,11(8):1400-1407.
23 Kashyap K T,Chandrashekar T.Effects and mechanisms of grain refinement in aluminium alloys[J].Bull Mater Sci,2001,24(4):345-353.
24 Zhang Ping,Li Qi,Zhao Junjun,et al..Analysis of secondary phases and measurement of volta potential of 7A52 aluminum alloy[J].The Chinese Journal of Nonferrous Metals,2011,21(46):1254-1257.张平,李奇,赵军军,等.7A52铝合金中第二相分析及微区电位测试[J].中国有色金属学报,2011,21(46):1254-1257.
2 Miller W S,Zhuang L,Bottema J.Recent development in aluminum alloys for the automotive industry[J].Mater Sci Eng A,2000,280(1):37-49.
3 Torkamany M J,Tahamtan S,Sabbaghzadeh J.Dissimilar welding of carbon steel to 5754 aluminum alloy by Nd:YAG pulsed laser[J].Mater Des,2010,31(1):458-465.
4 Murakami T,Nakata K,Tong H.Dissimilar metal joining of aluminum to steel by MIG arc brazing using flux Cored Wire[J].ISIJ Int,2003,43(10):1596-1602.
5 Mathieu A,Pontevicci S,Viala J C.Laser brazing of a steel/aluminium assembly with hot filler wire(88%Al,12%Si)[J].Mater Sci Eng A,2006,435-436:19-28.
6 Zhang Qiyun,Liu Shuqi.Selection of filler metal for aluminum brazing and it′s reaction with base metal[J].Acta Metall Sin,1981,17 (3):300-377.张启运,刘淑淇.高温铝钎料的选择及其与母材的相互作用[J].金属学报,1981,17(3):300-377.
7 Guo Jianting,Sun Chao,Tan Minghui,et al..Effect of alloying element on machanical properties of Fe3Al and Fe Al alloys[J].Acta Metall Sin,1990,26(1):20-25.郭建亭,孙超,谭明晖,等.合金元素对Fe3Al和Fe Al合金力学性能的影响[J].金属学报,1990,26(1):20-25.
8 Zhang Qiaoxin.Study on brittlement and possible solutions of intermetallic compounds[J].Rare Met Mater Eng,1990,20(6):27-31.章桥新.论金属间化合物的脆性及其克服途径[J].稀有金属材料与工程,1990,20(6):27-31.
9 Wang Liguo,Zhang Baofeng,Guan Shaokang,et al..Effects of RE,B on microstructure and properties of AM60 alloy[J].Rare Met Mater Eng,2007,36(1):59-62.王利国,张保丰,关绍康,等.RE,B对AM60合金显微组织和性能的影响[J].稀有金属材料与工程,2007,36(1):59-62.
10 Boag A,Hughes A E,Wilson N C,et al..How complex is the microstructure of AA2024-T3[J].Corros Sci,2009,51(8):1565-1568.
11 Akdeniz M V,Mekhrabov A O.The effect of substitutional impurities on the evolution of Fe-Al diffusion layer[J].Acta Mater,1998,46(4):1185-1192.
12 Zhang Lijuan,Zhou Dianwu,Liu Jinshui,et al..Laser welding of steel/aluminum dissimilar metal with powder addition[J].The Chinese Journal of Nonferrous Metals,2013,23(12):3401-3409.张丽娟,周惦武,刘金水,等.钢/铝异种金属添加粉末的激光焊接[J].中国有色金属学报,2013,23(12):3401-3409.
13 Zhou Dianwu,Peng Yan,Xu Shaohua,et al..Microstructure and mechanical properties of steel/Al alloy laser welding with Sn powder addition[J].Acta Metall Sin,2013,49(8):959-968.周惦武,彭艳,徐少华,等.添加Sn粉激光焊接钢/铝合金异种金属的显微组织与性能[J].金属学报,2013,49(8):959-968.
14 Segall M D,Lindan P L D,Probert M J.Effects of p-orbital on-site coulumb repulsion on the electronic properties of Mg2Sn[J].Condens Matter Phys,2002,14:2717.
15 Marlo M,Milman V.Desity-functional study of bulk and surface properties of titanium nitride using different exchange correlation functionals[J].Phys Rev B,2000,62(4):2899-2907.
16 White J A,Bird D M.Implementation of gradient-corrected exchange-correlation potentials in Car-Parrinello total-energy calculations[J].Phys Rev B Condous Matter,1994,50(7):4954-4957.
17 Hammer B,Hasnsen L B,Norkov J K.Improved adsorption energetic within density-fuctional theory using revised Perdew-BurkeErnzerhof functional[J].Phys Rev B,1999,59(11):7413-7421.
18 Simmons G,Wang H.Single Crystal Elastic Constants and Calculated Aggregate Properties[M].Cambridge:MIT Press,1971:80.
19 Shu X L,Hu W Y,Xiao H N,et al..Vacancies and antisites in B2 Fe Al and DO3 Fe3Al with a modified analytic EAM model[J].J Mater Sci Technol,2001,17(6):601-604.
20 Mehl M J,Osburn J E,Papaconstantopoulos D A.Structural properties of ordered high-melting-temperature intermetallic alloys from first-principles total-anergy calculations[J].Phys Rev B,1990,41(15):10311-10323.
21 Pugh S F.Relations between the elastic moduli and the plastic properties of polycrystalline pure metals[J].Philos Mag Series,1954,45(367):823-843.
22 Yu W Y,Wang N,Xiao X B,et al..First-principles investigation of the binary AB2 type Laves phase in Mg-Al-Ca alloy:Electronic structure and elastic properties[J].Solid State Sci,2009,11(8):1400-1407.
23 Kashyap K T,Chandrashekar T.Effects and mechanisms of grain refinement in aluminium alloys[J].Bull Mater Sci,2001,24(4):345-353.
24 Zhang Ping,Li Qi,Zhao Junjun,et al..Analysis of secondary phases and measurement of volta potential of 7A52 aluminum alloy[J].The Chinese Journal of Nonferrous Metals,2011,21(46):1254-1257.张平,李奇,赵军军,等.7A52铝合金中第二相分析及微区电位测试[J].中国有色金属学报,2011,21(46):1254-1257.